In general, a disk apparatus such as a hard disk drive (HDD) includes: magnetic disks within a casing, a spindle motor that supports the magnetic disks and rotates the magnetic disks, an actuator assembly that supports magnetic heads, a voice coil motor that drives this actuator assembly, a flexible printed circuit board unit for controlling these components, and the like.
The actuator assembly has an actuator block supported rotatably about a support shaft and a plurality of head gimbal assemblies (hereinafter, referred to as “HGAs”) supported by the actuator block via arms. The HGAs each include a suspension and a load beam, a flexure (an interconnection member) attached onto the load beam, and the magnetic head mounted on a gimbal portion of the flexure. Furthermore, the flexure has a connection end portion extending up to the actuator block, and this connection end portion is electrically joined to a flexible wiring board (FPC) attached to the actuator block.
The number of magnetic disks installed in the casing is on the increase these days with an increase in a memory capacity of the HDD. A so-called dual actuator assembly having two stacked actuator assemblies is proposed to handle a plurality of magnetic disks. When the plurality of magnetic disks is stacked, a gap between the two adjacent HGAs in each actuator assembly is normally approximately 0.15 mm. Because of this, when the two actuator assemblies are superimposed one above the other, it is also necessary to seta gap in a boundary between the actuator assemblies to approximately 0.15 mm.
However, the two actuator assemblies operate to rotate independently of each other. For this reason, a spacing of approximately 0.15 mm between the actuator assemblies is insufficient for ensuring smooth operation without interference with each other. A technique for reducing the number of magnetic heads or magnetic disks in a boundary portion or a technique for extending a stacking gap between magnetic disks have been proposed to ensure the sufficient spacing; however, a memory capacity of an entire disk apparatus decreases in either case.